Elsevier

Neuropsychologia

Volume 47, Issue 12, October 2009, Pages 2454-2463
Neuropsychologia

Enhanced detection of visual targets on the hand and familiar tools

https://doi.org/10.1016/j.neuropsychologia.2009.04.016Get rights and content

Abstract

This study investigated whether or not the simple detection of visual stimuli is better when those stimuli are presented on the hand than on other objects, and whether or not detection on other objects improves when people are trained to use them as tools. Participants performed a speeded visual detection task to targets presented on either side of their own left hand, a fake left hand, and a small garden rake. They were then trained to use either the fake hand or the rake as a tool with their left hand. Participants initially responded faster to stimuli projected onto their real hand than to stimuli presented on the fake hand or the tool, but they did not respond faster to stimuli on one side of the hand than on the other. After training, participants showed better detection of the visual stimuli presented on the object that they had been trained to use than they did for stimuli presented on the other object. Moreover, participants responded faster to stimuli presented on the upper side of the object that they had been trained to use than they did to stimuli on the other side. These findings demonstrate that an enhanced visual detection can be induced for stimuli presented on tools and other inanimate objects with training, suggesting that these objects have been incorporated into the body schema.

Section snippets

Participants

Thirty-two naïve volunteers (16 males and 16 females) from The University of Western Ontario took part in this study for class credits. All of the volunteers reported normal or corrected-to-normal visual acuity and were right-handed. The experiments were approved by the local ethics committee and all participants gave written informed consent.

Apparatus

In the Real Hand (RH) condition, the participants were asked to sit at a table with their head placed on a chinrest. Their left forearm was placed on the

Results

Because the order of experimental conditions within testing sessions was counterbalanced across participants, we felt that the most efficient way to analyze the data was to compute the mean RT across the 20 trials in each condition for each participant. Outliers that were more than two SDs beyond the original mean were not included in the computation of the final mean. Eliminated trials represented on average less than 2% of the total number of trials. All post hoc tests were

Discussion

Our results provide strong support for the idea that the detection of visual stimuli is enhanced when those stimuli are viewed on the surface of the hand. In other words, the participants in our study showed shorter reaction times for visual targets projected onto their own hand than they did for the same targets projected onto either a fake hand or a small garden tool. In fact, in a control experiment, we showed that detection of targets projected on a tool was no different than detection of

Conclusion

In this study, we found that visual stimuli are detected faster on one's own hand than on a fake hand or tool. Unlike visual guidance of pointing, simple visual detection is not better on skin with higher tactile-receptor density. After training with the fake hand or the tool, detection improves for targets presented on those objects. These findings provide strong support for the ‘body-view enhancement effect’ and the idea that this effect can be modulated by training such that new objects can

References (30)

  • M. Botvinick et al.

    Rubber hands ‘feel’ touch that eyes see

    Nature

    (1998)
  • A. Dufour et al.

    Improved visual sensitivity in the perihand space

    Experimental Brain Research

    (2008)
  • H.H. Ehrsson et al.

    That's my hand! Activity in premotor cortex reflects feeling of ownership of a limb

    Science

    (2004)
  • A. Farne et al.

    Dynamic size-change of hand peripersonal space following tool use

    Neuroreport

    (2000)
  • L. Fogassi et al.

    Coding of peripersonal space in inferior premotor cortex (area F4)

    Journal of Neurophysiology

    (1996)
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